ENVNANO Report Summary

The evaluation of the safety of engineered nanoparticles (ENPs) is a key element in reaching the full potential of the benefits offered by the novel properties of these materials. The current practice is that the existing test guidelines for chemical risk assessment are used for this purpose, though some technical changes may be needed. However, evidence in the scientific literature is emerging that these conventional methodologies for assessing chemical risks may not be appropriate for assessing risks associated with ENPs.

EnvNano challenges the assumptions behind the use of methods developed and optimized for dissolved chemicals by taking a starting point in the fact that particles behave fundamentally different than dissolved chemicals in the test systems used for risk assessment. During the whole project, experimental studies of engineered nanoparticles in ecotoxicity tests with algae and crustaceans have highlighted that understanding and quantification of the dynamic changes occurring to ENPs in water before and during testing may hold the key to a proper interpretation of test results obtained. As a result of the EnvNano project it is therefore to propose that multiple characterization methods are needed to interpret test results and that a combination of a shortened exposure period with an aging step of ENPs in medium prior to testing should be implemented to achieve increased control of exposures in ecotoxicity tests.

Results obtained in EnvNano for uptake and excretion of ENPs in freshwater crustaceans and zebrafish underline that the principles of assuming chemical equilibrium between test species and the surrounding environment, traditionally used for dissolved chemicals, are not valid for ENPs.While the literature on ecotoxicological effects and uptake of ENPs is rapidly expanding, the applicability of reported data of ENPs for hazard assessment purposes is questionable. A major knowledge gap that has been addressed in EnvNano is whether nanoparticle specific effects occur when test organisms are exposed to ENPs in aquatic test systems. This knowledge gap is not straightforward to fill, due to the high variability in ENP types, and the different behavior of ENPs compared to “ordinary” (dissolved) chemicals in the ecotoxicity test systems. The findings of EnvNano outline some of the pitfalls in aquatic toxicity testing of ENPs which may lead to misinterpretation of test results. Furthermore, a major outcome of EnvNano is to propose response types to account for in order to reveal potential nanoparticle specific effects in the aquatic test organisms used for risk assessments of ENPs.

The experimental findings in EnvNano are directly connected to the development of new risk evaluation approaches within the project frame. This has resulted in two frameworks for alternative risk evaluation of ENPs. Both of these are designed to operate under severe lack of data. The first framework is aimed at an operationalization and application of “early warning signs” to screen nanomaterials for harmful properties. It shows how the warning signs of novelty, persistency, bioaccumulation, dispersivity, and irreversible action can used as a first screening for potentially hazardous nanomaterials. The second framework is a conceptual tool for categorization and communication of exposure potentials and hazards of ENPs in consumer products. This framework has been fully implemented in the Nanodatabase (www.nanodb.dk).

The research carried out in EnvNano has expanded the fundamental knowledge base on the environmental risks related to ENPs and has been used to develop methods appropriate for assessing these. In this way strategies for identifying potentially problematic ENPs may be implemented at an early stage in the product development and safer alternatives may be found. In the light of the public concerns related to ENPs such knowledge is a pre-requisite to a successful large-scale commercialization of nanotechnology.